+0

# Trigonometry Small Angles Limit - 2

+1
485
2
+193

Hi...can you clarify logic in attached example marked with a question mark...Thanks and regards

Jan 31, 2019

#1
+112011
+3

The second does not come from the first, it comes from the BUT....

$$sin\frac{\theta}{2}<\frac{\theta}{2}\\ \qquad \text{remember that theta is describes as acute so therefore it is positive}\\ sin^2\frac{\theta}{2}<\left(\frac{\theta}{2}\right)^2\\ -sin^2\frac{\theta}{2}>-\left(\frac{\theta}{2}\right)^2\\ 1-sin^2\frac{\theta}{2}>1-\left(\frac{\theta}{2}\right)^2\\$$

Jan 31, 2019
#2
+193
+1

Thanks Melody for your patience and skills!

Feb 2, 2019